Anomalous exciton transport in response to a uniform, in-plane electric field

TL;DR

This paper demonstrates that Berry curvature can induce anomalous exciton transport in 2D materials under a uniform in-plane electric field, revealing a novel effect driven by electronic band topology.

Contribution

It introduces the concept that Berry curvature causes anomalous exciton transport in 2D materials, supported by semiclassical and quantum analyses, highlighting the role of Bloch oscillations.

Findings

Berry curvature leads to anomalous exciton velocities.

Exciton center of mass can move in response to a uniform electric field.

Transition metal dichalcogenide heterobilayers are promising for observing this effect.

Abstract

Excitons are neutral objects, that, naively, should have no response to a uniform, electric field. Could the Berry curvature of the underlying electronic bands alter this conclusion? In this work, we show that Berry curvature can indeed lead to anomalous transport for excitons in 2D materials subject to a uniform, in-plane electric field. By considering the constituent electron and hole dynamics, we demonstrate that there exists a regime for which the corresponding anomalous velocities are in the same direction. We establish the resulting center of mass motion of the exciton through both a semiclassical and fully quantum mechanical analysis, and elucidate the critical role of Bloch oscillations in achieving this effect. We identify transition metal dichalcogenide heterobilayers as candidate materials to observe the effect.